1. Field of the Invention
The present invention relates to a physiological signal sensing device, and more particularly, to a chip with its sensing method that is easy to operate for sensing physiological signals and improving the accuracy of records for electrocardiogram (ECG).
2. Description of the Related Art
It is known that the heart is an organ composed by muscles. However, the muscle that composes heart is different than other muscles (striated muscle, such as arms, legs, chest muscles). It is called “myocardium”. When the heart is active, current is generated by heart beating and electrocardiogram (ECG) is a picture that records the change of this current. From ECG, we can diagnose the shape changes of heart caused by arrhythmia and all kinds of heart diseases. From the changes of ECG, we can know whether the heart beating is regulative or not (i.e. arrhythmia). The main reason of causing arrhythmia is when there is a problem at a certain part or point of conduction system in heart. From the changes of different ECG pictures, we can understand which point of the conduction system is abnormal. In addition to the conduction system diseases, the changes of electrocardiogram follow the heart shape changed by whatever reasons. For example, when the workload of the heart is increased by long-term high blood pressure or heart valve diseases, myocardium hypertrophies will be thickened to cope with the increased workload. Meanwhile, the current of heart is also changed so as to change the shape of ECG. Therefore, from the changes of ECG, we can know if there is myocardium hypertrophy and also indirectly know if there is any cardiac disease to increase the workload of myocardium.
The present electrocardiogram or heart rate variability analysis facilities all complete the analysis and the collection of the electrocardiogram by customized lines and a customized program. These customized lines are comprised of complex amplifier circuit, and the analysis programs which are expensive and customized as well have to run in the very expensive PC or workstation. The price of hardware-related is often more than ten thousand NTD, and the price of computer is above twenty thousand NTD. The range of the price of software is large, which can range from two thousand to one million NTD. The total cost is extremely high, which would cause serious limit and impact on extension and application of this technology.
Because most of the electrocardiogram measuring instruments are very expensive and the size is large, most of the ECG is operated in hospitals; and very few people would like to purchase one to put at home. It would cause inconvenience to the people. Therefore, it is desirable to let people gain their own ECG correctly at any time without going to a hospital, which is a useful direction of thinking.